Conventionally, electronic equipment such as a digital camera or a personal digital assistant provided with a camera function includes a camera module with a solid-state imaging device. The solid-state imaging device includes a plurality of photoelectric conversion elements arranged in a two-dimensional array corresponding to respective pixels of an image. Each photoelectric conversion element performs photoelectric conversion where incident light is converted into a charge whose amount corresponds to an amount of light received, and stores the charge as a signal indicating brightness of each pixel.
Such a solid-state imaging device includes a front-surface-irradiation type solid-state imaging device and a back-surface-irradiation type solid-state imaging device. In the front-surface-irradiation type solid-state imaging device, the front surface of a semiconductor layer on which photoelectric conversion elements are arranged is the light receiving surface, and a wiring layer is formed on the light receiving surface. On the other hand, in the back-surface-irradiation type solid-state imaging device, the back surface of a semiconductor layer on which photoelectric conversion elements are arranged is the light receiving surface, and a wiring layer is formed on the front surface of the semiconductor layer.
In this manner, in the back-surface-irradiation type solid-state imaging device, the wiring layer does not reside on the light receiving surface for each photoelectric conversion element and hence, the back-surface-irradiation type solid-state imaging device receives the light more efficiently than the front-surface-irradiation type solid-state imaging device. However, in the back-surface-irradiation type solid-state imaging device, it is necessary to expose the light receiving surface of each photoelectric conversion element by decreasing a thickness of the semiconductor layer by grinding from the back surface side. Hence, a portion of light received passes through the semiconductor layer whose thickness is decreased thus giving rise to a drawback that light reception sensitivity is lowered.